Detergent composition



Patented Apr. 13, 1943 DETERGENT COMPOSITION Gilbert 0. Toone andLawrence H. Flett,

' N. Y., assignors to Allied Chemical & poration, a corporation of NewYork,

Hamburg, Dye Cor- No Drawing. Application October 20, 1938,

Serial No. 236,090

11 Claims.

The present invention relates to detergent compositions containing'as anessential detergent ingredient one or more water-soluble salts of alkylesters described more fully below. 'The invention more particularlyrelates to detergent compositions comprising one or more of these alkylester salts which compositions in the dry form or in the form ofsolutions are especially adapted for use as shampoos.

The alkyl ester salts which constitute the essential detergentingredient of the detergent compositions of the present invention arealkali metal salts (which term is meant to also include the ammoniumsalts) of sulfo aliphatic mono carboxylic alkyl esters (sulfo-fattyesters) containing 2 to 4 carbon atoms in the acyl radicals and 12 to 18carbon atoms in the alkyl radicals thereof. (Hereinafter, these estersare sometimes referred to as alkyl esters of sulfo aliphatic carboxylicacids, and sometimes simplyas alkyl ester salts.) These alkyl estersalts are derivable from sulfoacetic acid, sulfopropionic acid, and

sulfobutyric acid, and any of a wide variety of aliphatic alcohols (e.g., straight and branched chain aliphatic alcohols) containing 12 to 18carbon atoms. Inasmuch as alcohols of this class derived from naturallyoccurring fatty acids may be used in the preparation of the alkyl estersalts, the alkyl ester salts, when manufactured from said alcohols, areordinarily mixtures of compounds rather than single compounds; Anoutstanding example of this class of alkyl ester salts is the mixture ofsulfo acetates, designated lauryl sulfo acetate and prepared fromcommercial lauryl alcohol which is derived from the mixed fatty acidglycerides of cocoanut oil.

Although these alkyl ester salts have good detergent power, and areneutral in character, attempts to employ them alone or in an unmodifledform for cleaning applications in which their lathering properties areespecially desirable, and particularly for use as shampoos, have notbeen entirely successful. This is due to a number of factors related tothe requirements of an acceptable shampoo, and the properties of thealkyl ester salts. In order for a shampoo to'be commercially acceptable,it should have good la'thering power. Further, it should be an effectivecleansing agent for the hair and scalp, but it should possess little, ifany, of the objectionable property of removing too much oil from thehair and scalp and leaving these in an excessively dry state. Further,the aqueous solutions of the shampoo preferably should be stable over awide range of temperatures, and have a of viscosity.

The above alkyl ester salts in themselves do not have all these requiredproperties. Thusfor aqueous solutions of these alkyl ester salts aloneto have strong lathering powers, when used in fair degree the usualsmall amounts, the alkyl ester salts must be present in substantialconcentration. When using a concentrated aqueous solution of one ofthese alkyl ester salts, it has been found that the defatting power ofthe solution is such that when the solution is used in sufiicientamounts to produce a satisfactory lather, the 'defatting power of thesolution is, in general, too drastic, since it not only is eflective incleansing the hair and scalp, but also removes an excessive quantity ofthe natural oils from the hair and skin. In the case of barbers andbeauty parlor operators who, as a rule, manipulate shampoos with barehands, this would be especially objectionable because the removal of thenatural oils from their hands by the continual use of the solutionswould lead to cracking of the skin. Solutions of this type obviously areobjectionable if used as shampoos for dry hair and scalp.

These concentrated solutions sometimes have a further disadvantageresulting from the fact that the solubilities of these alkyl ester saltsin water vary greatly with changes in temperature. Thus, a concentratedaqueous solution of an alkyl 'ester in the form of a neutral salt; e.g., a sodium salt, may be prepared so as to-be perfectly clear at thetemperature of preparation. However, on lowering the temperature of sucha solution, it becomes supersaturated, and for a time persists as aclear solution and then precipitates to yield a cloudy solution orunsightly mixture. Aqueous mixtures which are cloudy 'or' which containunsightly precipitates are not acceptable to consumers.

It is an object of this invention to prepare detergent compositionswhich contain one or more alkali metal salts of alkyl esters of sulfoaliphatic carboxylic acids containing 2 to 4 carbon atoms in the acylradicals and 12 to 18 carbon atoms in the alkyl radicals thereof, whichcompositions are superior in their characteristics to compositionscontaining one or more of these alkyl ester salts only, and areparticularly well adapted for use as shampoos and for related purposes.

A further object of the invention is to provide compositions comprisingaqueous solutions containing one or more of the above-described alkylester salts, which compositions lather freely, and may be producedeconomically.

A further object of the invention is to provide compositions comprisingconcentrated aqueous solutions containing one or more of theabovedescribed alkyl ester salts, which solutions lather freely, andhave detergent power such that they may be used as shampoos withoutinjury to the hair, scalp, or skin.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

It has been discovered in accordance with the present invention thatdetergent compositions which contain as the essential detergent;ingredient one or more alkali metal salts of alkyl esters of sulfo 1,aliphatic carboxylic acids which contain 2.to 4 carbon atoms in the acylradicals and 12 to 18 carbon atoms in the alkyl radicals thereof andwhich are substantially free from the abovediscussed disadvantages ofthese alkyl ester salts when used alone can be prepared by associatingwith one or a mixture of these alkyl ester salts a compound of the classdescribed more fully blow. For simplicity in terminology, a compound ofthis class, whether used singly or in admixture with one or more othercompounds of the class, is referred to herein as a stabilizing agent.The compositions may be in the form of dry mixtures which are veryreadily soluble in water, and therefore can be applied directly to thehair and scalp. They may also be in the form of aqueous solutions whichare particularly adapted for use as shampoos for the hair and for thewashing of fine fabrics, upholstery and rugs.

Thus it has been found that by associating a stabilizing agent with analkyl ester salt of the above class, such as sodium lauryl sulfoacetate,

compositions are obtained which can be employed for the preparation ofconcentrated aqueous solutions which have lathering powers considerablyin excess of the lathering powers of solutions containing the sameamount of alkyl ester salt, but omitting the stabilizing agent. In fact,an aqueous solution which contains a mixture of an alkyl ester salt anda stabilizing agent in a certain total concentration of alkyl ester saltand stabilizing agent can be prepared which possesses substantially thesame lathering power as a solution having a concentration of alkyl estersalt alone equal to this total concentration. The compositions of thepresent invention in the form of aqueous solutions have the importantadvantage over solutions of alkyl ester salts alone in that, while theyhave substantially equal lathering powers and satisfactory cleansingproperties, they have weaker defatting properties and therefor, whenused for shampooing the hair, do not remove an excessive amount of oilfrom the hair, scalp, or skin.

Asbefore pointed out, it is important that commercial shampoos in theform of solutions should remain clear at relatively low temperatures;that is, they should have relatively low turbidity points. Thesurprising discovery has been made that by adding the stabilizing agentsto aqueous solutions of one of the above-described alkyl ester salts ofsutiicient concentration to be turbid to solid at room temperatures,solutions are formed which not only do not have higher turbidity pointsthan the aqueous solutions of the alkyl ester salts, but in such casesthe turbidity points are lower. Because of this property of thestabilizing agents, it has been found that aqueous solutions can beprepared having high total content of alkyl ester salt and stabilizingagent so that the solutions have excellent lathering properties and yet,despite the highly concen- I trated nature of the solutions, theirturbidity points are such that they may be handled and stored atordinary household temperatures without developing turbidity.

The stabilizing agents used in accordance with the present invention arecomposed of one or more compounds which are alkali metal salts (whichterm is meant to include also the ammonium salts) of mono alkyl sulfatesand of sulfo aliphatic monocarboxylic alkyl esters in which the alkylradicals contain 5 to 11 carbon atoms, but contain no straight carbonchain of more than 9 carbon atoms, and the organic acyl radicals contain2 to 4 carbon atoms. Th..s the stabilizing agents are composed of one ormore water-soluble monoalkyl esters of sulfuric acid, sulfoacetic acid,sulfopropionic acid, or sulfobutyric acid, wherein the alkyl groupscontain 5 to 11 carbon atoms, but not more than 9 carbon atoms in astraight chain. The compounds are preferably used in the form of theirneutral salts, such as their alkali metal (including ammonium) salts,particularly the sodium salts. It has been found that of the compoundsof this class those which contain 6 to 8 carbon atoms in the alkylgroups thereof, are generally to be preferred for use in the presentcompositions. larly it has been found that monoalkyl esters of the aboveclass in which the alkyl groups are octyl groups, especially2-ethyl-hex'yl groups, are particularly effective for use in thestabilizing agents. Specific examples of compounds which may be usedsingly or in the form of mixtures as stabilizing agents in thecompositions are the following: neutral sodium, potassium, ammoniumsalts of normal hexyl sulfoacetate, secondary hexyl sulfoacetate,mono-normal hexyl sulfate, mono-Z-ethyl-butyl sulfate, heptylsulfoacetates, normal octyl sulfoacetate, secondary octyl sulfoacetate,Z-ethyl-hexyl sulfoacetate, mono-2- ethyl-hexyl sulfate, 2'-ethyl-hexylsulfobutyrate, mono-nonyl sulfate, and an alkyl sulfoacetate in whichthe alkyl group contains 11 carbon atoms in a branched-chain in whichnot more than 9 carbon atoms are in a straight chain.

The stabilizing agents alone are at best weak lathering agents and insome cases display no lathering properties at all. Nevertheless, theseagents have surprisingly been found to possess the ability of increasingthe lathering properties of the long-chain alkyl ester salts describedabove. At the same time, since the stabilizing agents have substantiallyno defatting properties, the aqueous solutions of mixtures of the alkylester salts and stabilizing agents in general are' less drastic in theirdefatting action than aqueous solutions of the alkyl ester salts alonehaving the same lathering properties. The reason why the stabilizingagents do not raise the turbidity points of aqueous solutions of thelong-chain alkyl ester salts, but, instead act to lower the turbiditypoints of such solutions, is not clearly understood. Whatever thetheoretical explanation of the action of the stabilizing agents may be,the compositions of the present invention containing the stabilizingagents in association with the long-chain alkyl ester salts so combinethe excellent cleansing and lathering powers of the latter compoundswith the lather-inducing and stabilizing powers of the stabilizingagents that the concentrated aqueous solutions of the compositions arecharacterized by the controlled washing and 'high lathering qualities,and stability and clarity which are demanded of the highest qualityshampoos; yet they do not have the i excessive defatting powers that arean objectionable feature of the ordinary aqueous solutions of thelong-chain alkyl esters.

As previously indicated, the long-chain alkyl ester salts used in thecompositions of the present invention may be single compounds ormixtures of compounds, as, for example, the mixture of alkylsulfoacetates which contains a preponderating amount of monolauryl,monomyristyl, and monocetyl sulfoacetates, and which can be made Moreparticufrom the commercial lauryl alcohol obtained as a mixture ofalcohols resulting from the hydrogenation 'of the lower alkyl esters ofthe fatty acids of saponifled cocoanut oil. In referring to laurylsulfoacetate or other alkyl sulfoacetate herein and in the'claims, itwill be understood that the commercial product as well as thesubstantially pure compound is'intended.

While any of the above-described long-chain alkyl ester salts may beused in the present compositions, it has been found that particularlyvaluable compositions are obtained with the use of commercial laurylsulfoacetate, preferably in the form of the sodium salt. Compositionscontaining this compound and a stabilizing agent, especially astabilizing agent containing a compound having a 2-ethyl-hexyl group,have been found to be particularly valuable for use as shampoos.

The compositions of thepresent invention are conveniently prepared in asimple manner by mixing the long-chain alkyl ester salt and thestabilizing agent in the dry state in proportions such that theresulting mixture may be dissolved in water to produce an aqueoussolution having the desired properties of detergency. lathering. andsolubility; the components and proportions to be employed in anyparticular case being dependent upon the properties which it is desiredto have the resulting composition possess. Be-

cause of the variable properties of the compounds composing thestabilizing agents, in many cases it is preferred to employ astabilizing agent containing two or more compounds rather than oneconsisting of a single compound.

In connection with the proportioning of the components of thecompositions, it should also be noted that while the above-describedlongchain alkyl ester salts as a class possess the properties describedherein, individual members of the class differ one from another in thedegree in which they possess one or more of these properties. Hence, nogeneral rule as to the optimum specific proportions is applicable to allmixtures. However, it can be stated that the amount of stabilizing agentto produce the beneficial results of the present invention should not beless than three-fourths to one part by weight-for each part by weight ofthe alkyl ester salt or mixture of alkyl ester salts and as a generalrule the compositions preferably should not contain more than ten partsbyweight of stabilizing agent for each part by weight of the alkyl estersalt or mixture of alkyl ester salts. compositions of the inventioncontain from about one and one-half to about five parts, or better, fromabout one and one-half to about four parts. by weight of the stabilizingagent for each part by weight of the alkyl ester salt.

In preparing the compositions of the invention in the form of aqueoussolutions, in order for the solutions to possess adequate cleansing andlathering powers, it is necessary that the combined content oflong-clrain alkyl ester salt and stabilizing agent should constitute atleast five per" cent, and preferably at least ten per cent, by weight ofthe solutions. Further, to avoid high turbidity points, the solutionspreferably should not have more than fifty per cent combined content ofalkyl ester salt and stabilizing agent. In fact, for most purposes,solutions having such a combined content of not more than 35 per centare preferable. The preferred solutions, therefore, are those which havea combined The preferred alkyl ester salt and stabilizing agent contentof from 10 to 35 per cent.

When making up these solutions, it will be understood that theproportioning of theingredients will be dependent upon theconcentrations of the solutions as well as upon the specific longchainalkyl ester salts and stabilizing agents used. The preferred solutionsof the present invention are those which remain clear above 10 C. and,after being precipitated, clear up below 20 C. By applying the aboveprinciples with respect to the proportioning and selection ofingredients, concentrated solutions can be prepared having turbiditypoints of this nature.

A property of aqueous solutions of the longchain alkyl ester saltsintended for use as shamp005 and for related purposes which is of someimportance is the viscosity of the solutions. While this property is notan indication of the basic functional worth of the solutions, it doeshave an effect on their merchantability. It has been found that theviscosity of aqueous solutions of the alkyl ester salts may becontrolled by the amount and character of stabilizing agent incorporatedtherein. Thus it has been found that as the amount of stabilizing agentis increased in proportion to the amount of alkyl ester salt, theviscosity of the solution decreases to a minimum and then increasesrapidly.

In order to obtain a solution having the detergent and latheringproperties in the degree desired in a particular instance, whichproperties are dependent in some measure upon the specific properties ofthe alkyl ester salt and the stabilizing agent, it may not be feasibleto employ an amount of stabilizing agent such as to impart optimumviscosity characteristics to the solution. In many cases, however, it ispossible to prepare solutions having excellent viscositycharacteristics, and the desired detergent and lathering qualities, bytaking into account the above-mentioned property of the stabilizingagents when making up the compositions. As a feature of the invention,it has been found that the viscosity of highly concentrated solutions,say from 16 per cent to 50 per cent strength, can be increased by usingin the compositions highly solublestabilizing agents with or without thefurther addition of a compatible highly soluble salt such as ammoniumsulfate, sodium citrate, sodium tartrate,

sodium malate, etc. The viscosity of lower conhighly concentratedsolutions, say from 15 per cent strength, can be increased by theaddition of gums such as karaya, locust bean gum, gum tragacanth, etc.compositions not only increases the viscosity of their aqueoussolutions, but also increases the stability of the foam or lather whichthey produce on use. The aforementioned highly soluble salts also act asbuffers, and they may be added to solutions for this purpose, ifdesired.

The following examples are given to illustrate the invention. The partsin the examples are by weight:

Examples 1 to 3 illustrate the properties of the stabilizing agents ofincreasing the lathering properties (used herein to denote, generically,

foaming, frothing, and lathering properties) of the aqueous solutions ofthe long-chain alkyl ester salts. To demonstrate the lathring propertiesof the aqueous solutions, an apparatus was used consisting of a 500 cc.cylindrical graduate and a plunger consisting of a No. 9 rubber stopperor cork (having a top diameter of about 1% inches, a bottom diameter ofabout i inches, and a The addition of a gum to the v of the graduate ata rate of about two strokes per second for thirty seconds. The stopperor cork was of such a size that it slipped easily inside the cylinder.The solutions were tested at about the same temperature and the timeintervals were measured by a stop watch. After the lather was generated,the volume of liquidwhich had separated at the bottom of the graduatewas measured at half minute intervals for three minutes, and at oneminute intervals for the next two minutes. The smaller the amount ofliquid separated, the greater was the lathering power of the testedsolutions.

EXAMPLE 1.Three aqueous solutions were pre-- pared as follows: f

Solution #1.One part by weight of commercial sodium lauryl sulfoacetate(prepared from commercial lauryl alcohol obtained by the reduction ofthe fatty acids derived from cocoanut oil) was dissolved in 100 partswater.

Solution #2.One part by weight of commer cial sodium 2-ethyl-hexylsulfoacetate was dissolved in 100 parts water.

Solution #3.One part by weight of a mixture of equal weights of sodiumlauryl sulfoacetate and sodium Z-ethyl-hexyl sulfoacetate was dissolvedin 100 parts water.

Each of the solutions was tested for lathering qualities in the mannerdescribed above. The results obtained are recorded in the followingtable, in which the average experimental error is about two units at thefive minute interval:

It will be seen from the results obtained with Solutions #1 and #3 thatby replacing one-half of the sodium lauryl sulfoacetate in Solution #1with sodium Z-ethyl-hexyl sulfoacetate, a solution is obtained (Solution#3) having substantially the same lathering properties. This issurprising since the results obtained with Solution #2 show that sodium2-ethyl-hexy1 sulfoacetate has weak lathering properties. This example,therefore, illustrates an important advantage characterizing the presentcompositions; i. e., aqueous solutions of the compositions of thepresent invention having a certain total concentration of long-chainalkyl ester salt and stabilizing agent having lathering propertiescomparable to the lathering properties of solutions having aconcentration of the same alkyl ester salt alone equal to this totalconcentration.

EXAMPLE 2.The lathering qualities of aqueous solutions at differentconcentrations of sodium lauryl sulfoacetate, of sodium 2-ethyl-hexylsulfoacetate, and of a mixture of these were determined in the foregoingmanner. The following table summarizes the results obtained:

cgmtggsifioln (if es so ut on n Amount liquid in 00. separated from zggg g ggi lather obtained from treatment of 50 (x3. mug agent pet ofsolution in desi nated time intervals 100 0c- Sodium Sodium lauryl 1 2 314 1 1% 2 2% 3 4 5 sulroe y min. min. min. min min. min. min. min.acetate acetate 0 1 1 2 5 6 12 18 (i 1 3 5 7 10 21 0 1 3 5 8 11 26 3 711 15 19 22 26 29 6 14 19 27 29 33 35 0. 10 41 44 44 44 45 46 46 0. 1937 42 44 45 45 45 45 46 0. 28 33 39 41 42 43 44 '15 45 0. 40 12 21 27 3134 37 40 41 0. 5 12 18 23 28 32 37 40 0.10 0 0 1 2 4 6 10 15 0.19 0 0 l3 5 6 12 18 O. 28 0 0 1 3 5 7 2 19 O. 40 0 0 2 4 6 8 15 21 These resultsshow clearly that the lathering properties of alkyl ester salts areimproved by mixing the said detergents with stabilizing agents which perse have little, if any, lathering properties. In some instances thelathering power of the mixtures has been found to be even greater thanthat of a detergent solution of equal concentration. (For example,compare 3, 4 and 5 minute readings of horizontal row 1 with those ofhorizontal rows 11 and 12 in the above table.)

EXAMPLE 3.-Comparisons were made of the lathering qualities of aqueoussolutions of sodium lauryl sulfoacet-ate and of mixtures of thisdetergent with each of the following stabilizing agents (the octyl groupof these agents is the Z-ethyl-hexyl group) (a) Sodium octyl sulfate(1)) Sodium octyl sulfoacetate The results of the several tests aresummarized in the following tables:

Table 1 LIQUID SEPARATION FROM LATHER GENERATED WITH A SOLUTIONCONTAINING 0.5 GRAM SODIUM LAURYL SULFOACETATE PER CC. OF SOLUTIONElapsed time in minutes kiln/22143 4 s No. of cc. of liquid separation 01 l 2 5 6 12 18 Table 2 LIQUID SEPARATION FROIVI LATHER GENERAIED W'ITHSOLUTIONS CONTAINING 0.2 GRAM SO'DIUIVI LAURYL SULFOACETATE AND 0.3 GRAMOF STA- BILIZING AGENT PER 100 CC. OF SOLUTION Elapsed time in minutesSolutions containing:

No stabilizing agent 1 5 s 11 14 1s 24 29 Sodium octyl sulfate 0 1 3 4 610 16 23 Sodium octyl sulfoacetate 0 0 l 3 4 7 l3 l8 Table 3 Elapsedtime in minutes Solutions containing:

No stabilizing agent 6 14 19 23 27 29 33 35 Sodium octyl sullate 1 3 5 7ll 15 23 28 Sodium octyl sulfoacetate 0 l 2 4 6 ll 19 Table 4 LIQUIDSEPARATION FROM LATHER GENERATED \VITH SOLUTIONS CONTAINING 0.05 GRAMSODIUM: LAURYL SULFOACETATE AND 0.45 GRAML STABILIZ- ING AGENT PER 10000. OF SOLUTION Elapsed time in minutes Solutions containing:

No stabilizing agent ll 25 29 32 35 35 36 38 Sodium octyl sullate 2 4 812 17 20 27 30 Sodium octyl sulfoacetate 0 1 3 5 8 13 20 Composition of100 parts of 5 solution Tub 'lurbidityd agg Solution appeare No. Sodiumon gg lauryl hexyl Water coolmg heating sullo- Sun-m to acetate acetateC'. C. 26 74 53 70 90 36 10 16 74 2 21 l0 10 80 6 26 10 5 85 10 29 5 9510 30 2 3 95 2 18 3 2 95 2 S7 Solution No. 1 above, a 26% solution ofsodium lauryl sulfoacetate in water, on being cooled slowly, becomesslightly turbid at about 53 C., milky and thick at about 35 0., pasty atabout 27 C., and solid at about C. When heated slowly, the mass becomesclear liquid at about 70 C.

The results recorded in the foregoing table show the surprising efiectwhich the addition of a stabilizing agent composed of sodium2-ethylhexyl sulfoacetate has on the turbidity points of aqueoussolutions of a representative alkyl ester salt, sodium laurylsulfoacetate. Because of this efiect, aqueous solutions of sodium laurylsulfoacetate which remain clear at low temperatures may be preparedcontaining an amount of sodium lauryl sulfoacetate such that, in theabsence of the sodium 2-ethyl-hexyl sulfoacetate, the solutions wouldbecome turbid at a relatively high temperature.

EXAMPLE 5.-In a manner similar to that described in Example 4, a mixtureof 10 per cent sodium lauryl sulfoacetate, 16 per cent sodium2-ethyl-hexyl sulfate, and 74 per cent water was made.= It showed noturbidity at -7 C.

EXAMPLE 6.Aqueous solutions containing the specified quantities ofsodium lauryl sulfoacetate, stabilizing agents and water shown in thefollowing table were prepared. The temperatures in degrees centigrade atwhich turbidity appeared on cooling'and at which turbidity disappearedon warming the turbid liquids were determined. The results obtained aresummarized in the following table: I

9 parts of sodium lauryl sull'oacetate dissolved with- Partsstabilizingagont 0 9 18 36 Parts water 91 82 73 Total parts =l00.

Temperature in degrees oentigrade at Nature of stabilizing whichhumansagent Ap. Dis. Ap. Dis. Ap. Dis. Ap. Dis.

Sodium secondary hexyl sulioacetate 20 35 13 32 2 22 0 8 Sodium heptylsulloacetate 20 35 20 31 13 31 8 28 Sodium 2-ethyl-hexyl sulfoaoetate 2035 1 22 3 15 35 46 Sodium 2-ethyl-hexyl sulfate 20 35 2 l8 2 0 8 3Sodium 2'-Ethyl-hexyl sulfobutyrate i. 20 35 2 28 2 22 7 8 Sodiumn-hexyl sulloacetate 20 35 4 41 6 l8 9 4 Sodium n-ootyl sulioacetate .s20 35 2 39 2 ,34 3 10 Ap.=appeared. Dis.=disappeared.

This example illustrates the efiects of the specified stabilizing agentsin reducing the tur- ,bidity points of-aqueous solutions of a long-chainalkyl ester salt; in this case, sodium lauryl sulfoacetate. It alsoshows that the compounds composing the stabilizing agents, although theyexhibit the valuable propertieshereinbefore pointed out in an importantdegree, differ one from another in particular cases. Because of thisfact, in preparing the compositions of the present invention, it isadvisable to select the stabilizing agent and its proportion with a viewto the specific properties which it compositions possess.

As already stated, as a general rule, the addition of a stabilizingagent to a concentrated aqueous solution of a long-chain alkylester'salt first decreases the viscosityof the solution and then, as theamount of the stabilizing agent in the solution is increased, theviscosity of the solution is increased. The following example offersspecific illustrations of the effect of the stabilizing agents on theviscosities of an aqueous solution of an alkyl ester salt.

EXAMPLE 7 .An aqueous solution, containing 9 parts of sodium laurylsulfoacetate and 91 parts water was warmed to about 32 C. andtransferred to a 25 cc. pipette in which it was allowed to cool to 30 C.The time in seconds required to run the solution out of the pipette fromthe 25 cc. mark was noted. In the same manner, other solutions whichcontained 9 parts of sodium lauryl sulfoacetate and specified amounts ofstabilizing agents and water were made, and times in seconds required torun 25cc. portions of the respeois desired to have the acetate and 10parts ammonium sulfate.

tive solutions at 30 C. from the pipette were noted. The time intervalsthus recorded indicated the relative viscosities of the severalsolutions. The results obtained are recorded in the following table:

Tested solutions contained 9 parts of sodium lauryl sulfoaoetate and-From the results recorded in the above table, it will be seen that bythe proper selection of a stabilizing agent, and the use of it in themost desirable proportions in relation to the alkyl ester salt, it ispossible to prepare solutions having viscosities greater than theviscosity of the aqueous solution of the alkyl ester salt in the absenceof the stabilizing agent.

The following examples illustrate preferred compositions of theinvention containing a proportion ofstabilizing agent within the limitsof about 1 to about 4 .parts by weight of a stabilizing agent for eachpart by weight of the alkyl ester salt. The com-positions also contain ahighly water-soluble salt which has the effect of increasing theviscosity of the aqueous solutions.

' EXAMPLE 8.-10 parts of commercial sodium lauryl sulfoacetate,identified in Example 1, are mixed with 16 parts sodium 2-ethyl-hexylsul lffie mixture dissolved in 64 parts water furnishes a concentratedsolution which, in terms of flow time as indicated above, has aviscosity requiring 85 seconds of flow for 25 cc, as compared with waterwhich requires 26 seconds, and when the solution is cooled, turbidityappears at C. anddisappears, on warming, at C.

This concentrated solution is especially adapted for use as a shampoo,although it is also valuable for other purposes, such as for the washingof fine fabrics, rugs, and upholstery. It may be handled and storedunder the usual conditions without developing turbidity, because of itslow turbidity point. I

Exams 9.--10 parts of commercial sodium lauryl sulfoacetate are mixedwith 16 parts sodium capryl (secondary octyl) sulfoacetate and 10 partsammonium sulfate. The mixture dissolved in 64 parts water furnishes aconcentrated solution which on cooling develops turbidity at 4 C. andthe turbid solution, on being warmed, becomes clear at C. Thisconcentrated solution, similarly to that disclosed in Example 8, isparticularly valuable when employed as a shampoo.

The composition of this example, when compared with the composition ofExample 8, illustrates the superior properties of the 2-ethyl-hexylcompound as compared with the capryl (secondary octyl) compound; 1. e.,while compositions containing, the capryl compound exhibit improvedproperties as compared with compositions containing the long-chain alkylester salts alone, the 2-ethy1-hexyl compound imparts particularlyvaluable properties to the compositions.

EXAMPLE 10.-A composition containing 8 parts 0., compared with water at26 seconds; when the solution was cooled, turbidity appeared at 0 C.,and when the turbid solution was warmed, turbidity disappeared at 10 C.

The following examples illustrate shampoo compositions of the inventionwhich contain stav bilizing agents composed of a mixture of compounds, ahighly water-soluble salt, and a gum:

ExAMPLE 11.-A shampoo composition in the form of an aqueous solution ismade by mixing 4 parts of commercial sodium lauryl sulfoacetate with 9parts of sodium 2-ethyl-hexyl sulfoacetate, 4 parts sodium normal hexylsulfoacetate, and 2 parts of trisodium citrate crystals, and adding theaqueous solution prepared from 1 part of powdered gum karaya, and partsof Water. The resulting solution has a turbidity point of --4 C. and theturbid mixture clears at 0 C.

EXAMPLE l2.4 parts of commercial sodium lauryl sulfoacetate areintimately mixed with 11 parts of sodium 2-ethy1-hexyl sulfoacetate, 4parts of sodium Z-ethyl-butyl sulfate, and 2 parts of trisodium citratecrystal This mixture is added to a. solution of 1.2 parts of powderedgum karaya in 77.8 parts of water. The aqueous solution thus formed isadapted for use as a shampoo. It becomes turbid at 4.5 C. and the turbidmixture clears at =0.5 C.

In. place of the long-chain alkyl ester salts, stabilizing agents, andwater-soluble salts employed in the foregoing examples, there may beemployed in the compositions of the invention any of the other membersof these classes of compounds hereinbefore disclosed.

From the foregoing description it will be apparent that the presentinvention provides compositions having good lathering properties andcontrolled detergent power. In the form of aqueous solutions, thecompositions remain clear over a wide range of temperatures and havegood viscosity characteristics. The compositions and their aqueoussolutions, therefore, are admirably adapted for use as shampoos and forwashing fine fabrics, rugs, and upholstery.

Since certain changes may be made in the compositions disclosed withoutdeparting from the scope of the invention, all matter contained in theabove description should be taken as illustrative and not in a limitingsense.

We claim:

1. A detergent composition adapted for use as a shampoo comprising analkali metal salt of a long-chain alkyl ester of a suite aliphaticmonocarboxylic acid containing 2 to 4 carbon atoms in the acyl radicaland 12 to 18 carbon atoms in the alkyl radical thereof, and for eachpart by weight of said alkali metal salt of a long-chain alkyl ester, atleast three-fourths part by weight of a 1 stabilizing agent composed ofat least one compound which is an alkali metal salt of a monoallwl esterof an acid selected fromthe group consisting of sulfuric acid and sulfoaliphatic mono-carboxylic acids containing 2 to 4 carbon atoms, saidmonoalkyl ester salt containing 5 to 11 carbon atoms but not more than 9carbon atoms in a straight chain in the alkyl radical thereof.

2. A detergent composition adapted for use as a shampoo comprising analkali metal salt of a long-chain allgvl ester of sulfoacetic acidcontaining 12 to 18 carbon atoms in the alkyl radical thereof, and foreach part by weight of said alkali metal salt of a long-chain alkylester threefourths to ten parts by weight of a stabilizing agentcomposed of at least one compound which is an alkali metal salt of amonoalkyl ester of sulfoacetic acid containing to 11 carbon atoms butnot more than 9 carbon atoms in a straight chain in the alkyl radicalthereof.

3. A detergent composition adapted for use as a shampoo comprising analkali metal salt of a long-chain alkyl ester of sulfoacetic acidcontaining 12 to 18 carbon atoms in the alkyl radical thereof, and foreach part by weight of said alkali metal salt of a long-chain alkylester threefourths to ten parts by weight of a stabilizing agentcomposed of at least on compound which is an alkali metal salt of amonoalkyl ester of sulfuric acid containing 5 to 11 carbon atoms but notmore than 9 carbon atoms in a straight chain in the alkyl radicalthereof.

4. A detergent compositionadapted for use as a shampoo comprising sodiumlauryl sulfoacetate, and for each part by weight of said sodium laurylsulfoacetate one and one-half to five parts by weight of a stabilizingagent composed of at least one compound which is an alkali metal salt ofa monoalkyl ester of an acid selected from the group consisting ofsulfuric acid and sulfo aliphatic mono-carboxylic acids containing 2 to4 carbon atoms, said monoalkyl ester salt containing 6 to 8 carbon atomsin the alkyl radical thereof.

5. A detergent composition adapted for use as a shampoo comprising analkali metal salt of a long-chain alkyl ester of sulfoacetic acidcontaining 12 to 18 carbon atoms in the alkyl radical thereof, for eachpart by weight of said alkali metal salt of a long-chain alkyl ester oneand one-half to five parts by weight of a stabilizing agent composed ofat least one compound which is an alkali metal salt of a monoalkyl esterof an acid selected from the group consisting of sulfuric acid and sulfoaliphatic mono-carboxylic acids containing 2 to 4 carbon atoms, saidmonoalkyl ester salt containing 5 to 11 carbon atoms but not more than 9carbon atoms in a straight chain in the alkyl radical thereof, a highlywatersoluble salt selected from the group consisting of ammoniumsulfate, sodium citrate, sodium tartrate, and sodium malate, and a gumselected from the group consisting of gum karaya, locust bean gum, andgum tragacanth.

6. A detergent composition adapted for use as a shampoo comprising anaqueous solution of a sodium salt of a long-chain alkyl ester of a sulfoaliphatic mono-carboxylic acid containing 2 to 4 carbon atoms in theacyl radical and 12 to 18 carbon atoms in the alkyl radical thereof, andfor each part by weight of said sodium salt of a long-chain alkyl esterone and one-half to five parts by Weight of a stabilizing agent composedof at least one compound which is an alkali metal salt of a monoalkylester of an acid selected from the group consisting of sulfuric acid andsulfo aliphatic mono-carboxylic acids containing 2 to 4 carbon atoms,said monoalkyl ester salt containing 5 to 11 carbon atoms but not morethan 9 carbon atoms in a straight chain in the alkyl radical thereof,said aqueous solution having a total concentration of said sodium saltof a longchain alkyl ester and said stabilizing agent of 5 to 50 percent.

7. A detergent composition adapted for'use as I a shampoo comprising anaqueous solution of an by weight of said alkali metal laurylsulfoacetate at least three-fourths part by weight of a etabilizingagent composed of at least One compound which is an alkali metal salt ofa monoalkyl ester of an acid selected from the group consisting ofsulfuric acid and sulfo aliphatic mono-carboxylic acids containing 2 to4 carbon atoms, said monoalkyl ester salt containing 5 to 11 carbonatoms but not more than 9 carbon atoms in a straight chain in the alkylradical thereof, said aqueous solution having a total concentration ofsaid alkali metal lauryl sulfoacetate and said stabilizing agent of 5 to50 per cent.

8. A detergent composition adapted for use as a shampoo comprising anaqueous solution of sodium lauryl sulfoacetate, a highly water-solublesalt selected from the group consisting of ammonium sulfate, sodiumcitrate, sodium tartrate, and sodium malate, and for each part by weightof said sodium lauryl sulfoacetate threefourths to ten parts by weightof a stabilizing agent composed of at least one compound which is analkali metal salt of a monoalkyl ester of an acid selected from thegroup consisting of sulfuric acid and sulfo aliphatic mono-carboxylicacids containing 2 to 4 carbon atoms, said monoalkyl ester saltcontaining 6 to 8 carbon atoms in the alkyl radical thereof, saidaqueous solution having a total concentration of said sodium laurylsulfoacetate and said stabilizing agent of 5 to 50 per cent.

9. A detergent composition adapted for use as a shampoo-comprising anaqueous solution of sodium lauryl sulfoacetate, a salt selected from thegroup consisting of ammonium sulfate, sodium citrate, sodium tartrate,and sodium malate, and a gum selected from the group consisting of gumkaraya, locust bean gum, and gum tragacanth, and for each part by weightof said sodium lauryl sulfoacetate one and one-half to five parts byweight of a stabilizing agent composed of at least one compound which isa sodium salt of a monoalkyl ester of an acid selected from the groupconsisting of sulfuric acid and sulfo aliphatic mono-carboxylic acidscontaining 2 to 4 carbon atoms, said monoalkyl ester salt containing 6to 8 carbon atoms in the alkyl radical thereof, said aqueous solutionhaving a total concentration of said sodium lauryl sulfoacetate and saidstabilizing agent of 10 to 35 per cent.

10. A detergent composition adapted for use as a shampoo comprising anaqueous solution of sodium lauryl sulfoacetate, a salt selected from'alkali metal lauryl sulfoacetate, and for each part the groupconsisting of ammonium sulfate, sodium citrate, sodium tartrate, andsodium malate, and for each part by weight of said sodium laurylsulfoacetate one and one-half to five parts by weight of sodium2-ethy1-hexyl sulfoacetate, said aqueous solution having a totalconcentration of said sodium lauryl sulfoacetate and said 2-ethylhexylsulfoacetate of 10 to 35 per cent.

11. A detergent composition adapted for use as a shampoo comprising anaqueous solution of about 4 parts by weight of sodium laurylsulfoacetate, about 9 parts by weight of sodium 2- ethyl-hexylsulfoacetate, about 4 parts by weight of sodium normal hexylsulfoacetate, about 2 parts by weight of trisodium citrate, and about 1part by weight of gum karaya, said aqueous solution having a totalconcentration of saidv sodium lauryl sulfoacetate, said sodium2-ethyl-hexyl sulfoacetate, and said sodium normal hexyl sulfoacetate of10 to 35 per cent.

GILBERT C. TOONE. LAWRENCE H. FLE'II.

' Patent No. 2,516,19h.

CERTIFICATE OF CORRECTION.

April 15, 19M.

GILBERT c. T001133, ET AL.

It is hereby certified that error appears in the printed specificationoi the above mnnbered patent requiring correction as'follows: PageZ'Qfirst column, line 11, for "blow" read -below--; line M5, for"therefor" read --therefore-; page 5, second column, line 14.5, for"from 16" read '--from 15-; line 51 after lower strike out con-"g line52, before concentrated" strike out highly; same line, aiter "from"insert --5 per cent to--; page 11., first column, line 69, for 'fhaving"read --have--; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 15th day of June, A. D. 19,15.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

' Patent No. 2,516,19h.

"the same may conform to the record ofthe CERTIFICATE or CORRECTION.

April 15; 19h}.

GILBERT c. room-g, ETIAL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction aafollows: Page 2',first column, line 11; for blow read --below--; line 145, for-"therefor" read line 11.5,for ffrom l6" read'--from l5-- lihe 51, after"lower" strike out-com; line 52, before "concen- 'trated" strike out"highly"; same line, after "from" insert --5 per cent to----; page 11.,first column, line 69, for "having" read --he.ve--; and that the said'Letters Patent should be read with this correction"therein that case inthe Patent Office.

-therefore--; page 5, second column,

Signed and sealed this 15th day r June, A. D. 19h}.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

